The invention relates to a peripheral pump
From German Patent Application DE 40 20 521 A1, a peripheral pump is known that includes a circular-cylindrical impeller revolving in a pump chamber; on at least one of its two end faces, the impeller has a ring of vanes spaced apart from one another in the circumferential direction of the impeller, and viewed in terms of the longitudinal section through the pump, a bottom of the groovelike gap between two adjacent vanes forms a circular segment whose center is virtually identical to the center of another circular segment that is formed by the bottom of an annular feed conduit, which is disposed facing the ring of vanes, each in one wall of the pump chamber. Peripheral pumps of this kind, even after only a relatively short time in operation, show that the impeller is subject to considerable wear, which is due to an axial force that builds up in the peripheral pump, acts on the impeller, and presses the impeller in particular against an intake-side wall of an intake cap. Such a peripheral pump also has poor startup performance. Moreover, the axial force that builds up in the fuel feed unit leads to poor noise abatement.